high productivity for well implant applications varian medium current position paper

8/3/2019 HIGH PRODUCTIVITY FOR WELL IMPLANT APPLICATIONS VARIAN MEDIUM CURRENT POSITION PAPER

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HIGH PRODUCTIVITY FOR WELL IMPLANT APPLICATIONS

VARIAN MEDIUM CURRENT POSITION PAPER Rev. 1 (5-13-05)

Abstract - As devices have scaled below 100nm gate length, all transistor parametric implants

such as deep and shallow well implants as well threshold control (Vt) implants have migrated to

normal incidence implant. While the initial motivation was solely based on avoiding shadowing

and increase packing density, other factors such as defect reduction and reduced process

complexity are also becoming important factors. The architecture of the VIISta 810XE medium

current implanter and VIISta 3000 high energy implanter provides the unique ability to cover the

entire dose-energy requirements of the channel and well doping with true zero degree implants.

In this paper we will illustrate how this capability can be leveraged to maximize the utilization of

medium current and high-energy implanters and lower the overall cost of ownership. In addition,

we describe the complete process transferability across the VIISta implanters with a case study of

a typical CMOS recipe set.

I. INTRODUCTION

The IC industry is now undertaking the aggressive adoption of deep sub-micron CMOS devices

fabricated on 300mm wafers. Leading edge IC manufacturers are in high volume production on

300mm wafer production on the 130-150nm IC technology node, with 90-110nm and 65-70nm

technology nodes following soon [1]. The traditional dose and energy requirements to meet the

needs of these emerging applications are changing. There is a trend in reduced dose and energy

requirements for the latest generation of devices. This is altering the applications space that was

formally covered by high energy implantation. In the well applications area many of the implants

that were formally covered by high energy implantation can now be readily handled by this new

breed of medium current implanter.


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As a new breed of medium current ion implanters are introduced and a paradigm shift occurs, the

ability to extend the traditional operating range into the high energy operating space has been

provided. The result of this extension in operation for medium current machines provides a high

level of productivity for well implant applications. As well implant recipes move to medium

current implanters the number of high energy implanters can be reduced. This also provides

greater flexibility as a high energy implant back-up. The reduced operating costs of the medium

current machine offer substantial benefits in terms of capital productivity [2].

The key challenges faced in delivering this additional capability fall into a number of categories.

Extended energy range operation must be provided which guarantees robust performance for

single charge boron up to 300 keV and double charge boron up to 600 keV. Also, robust

performance for single charge phos up to 300 keV, double charge to 600 keV and triple charge to

900 keV. Long term stability in this extended operating range is critical to delivering reliable

process performance.

Substantial increases in productivity must be provided in order for the migration of well implant

recipes to medium current machines to make economic sense. Delivering increased productivity

at a lower cost of ownership will be a key figure of merit.

The operation at higher power levels for well implant applications creates additional issues when

photoresist wafers are utilized. The generation of an ion beam and its impact into photoresist-

masked wafers will have an adverse effect on the vacuum of a medium current ion implanter.

This is particularly significant when implanting with higher energies and higher beam current

through thick photoresist. Compensation methods must be provided to deal with Rs shift due to

photoresist outgassing. The ability to deliver a production-worthy solution to minimize Rs shift

under varying recipe and photoresist conditions will be required.


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There are some additional device fabrication challenges that have implications for equipment

selection as well. For well and channel formation, device scaling is driving n+/p+ spacing, low

doping concentration in the well/channel region and symmetrical well junction profiles. There

are implications for high energy ion implanters (and medium current as well) where advanced

devices can no longer tolerate shadowing effect and angle variation associated with a non-zero

degree well implant [3]. These are requirements for well implant technology that will impact ion

implanter architecture considerations. It is critical that the equipment be able to provide precise,

zero degree implant capability to satisfy well implant requirements.

There are two major limitations of current well implant capabilities. The first is that increasing

well concentrations results in new challenges. For smaller devices, substrate concentration needs

to be increased to maintain adequate isolation characteristics. Also, increased well concentration

results in increase junction leakage and junction capacitance.

Figure 1 : Well concentration and junction leakage requirements.

-2 .0

-1 .0

0 .0

1 .0

2 .0

1 .E -1 1 1 .E -1 0 1 .E -0 9 1 .E -0 8

J u n c t io n L e a k ( A )

Frequency()

N +/P-Well junction leak

N + - N W S p a c in g (u m )

N +S/D to P-Well

0

2

4

6

8

1 0

1 2

1 4

0 .0 0 .1 0 .2 0 .3 0 .4

BV

(V)

L o w D o s eH i g h D o s e

L o w D o s eH i g h D o s e-2 .0

-1 .0

0 .0

1 .0

2 .0

1 .E -1 1 1 .E -1 0 1 .E -0 9 1 .E -0 8


Frequency()


-2 .0

-1 .0

0 .0

1 .0

2 .0

1 .E -1 1 1 .E -1 0 1 .E -0 9 1 .E -0 8


Frequency()



N +S/D to P-Well

0

2

4

6

8

1 0

1 2

1 4

0 .0 0 .1 0 .2 0 .3 0 .4

BV

(V)


N +S/D to P-Well

0

2

4

6

8

1 0

1 2

1 4

0 .0 0 .1 0 .2 0 .3 0 .4

BV

(V)

N +S/D to P-Well

0

2

4

6

8

1 0

1 2

1 4

0 .0 0 .1 0 .2 0 .3 0 .4

BV

(V)

L o w D o s eH i g h D o s eL o w D o s eH i g h D o s e

L o w D o s eH i g h D o s eL o w D o s eH i g h D o s e


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There area additional limitations associated with tilted implants limiting device scaling. Tilted

implantation degrades inter-well isolation due to shadowing. The impact is more severe with

higher aspect ratios and thick photoresist.

Figure 2 : Limitations of tilted implant device scaling.

One of the issues associated with batch implanter technology is that true zero is not achievable.

A batch system will experience angular variation that exceeds the critical angle. The systems

must be run in quad mode at non-zero degree (~3-7 deg) to achieve desired uniformity. In this

mode the batch system cannot deliver the benefits of true zero degree implants.

Resist

STI

'encroachment'

P+Implantation (N-well)

Resist

STI

'shadowing'

B+Implantation (P-well)

0

2

4

6

8

1

- 0. 0. 0. 0.N+-NW Spacing

B

V

P-well

N +

Resist edge

N-wellP-

N +

Resist edge 0 0.5

7 Degree Tilted Implant onTest Structure

N

NW

N

MinimumSpacing

Non-

Shadowe

Beam

Induces Tilt AngleVariation

Batch Disk with P edestalsat Offset Angle(Cone Angle)

Cone Angle

Beam

Beam


Beam



Cone Angle

Beam


Cone Angle

Beam

Cone Angle

Beam


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Figure 3 : Cone angle effect on batch system implanter.

It is critical to provide a parallel beam with precise angle control to achieve a true zero degree

implant. The precise control of the ion beam and beam parallelism will be required to maintain

uniform distribution within the wafer as depicted in Figure 4 below.

Junct ion Depth

Un i fo rm , ze ro

deg ree imp lan t

D i f f e rent ia l Chan ne l ing

due to cone an g le e f fec t

1282.3 /0 .568%

V I IS ta 3 0 0 0 H P

1406 .7/

4 .946%

Batch H E Sys tem

Junct ion Depth

Un i fo rm , ze ro

deg ree imp lan t



Junct ion DepthJunct ion Depth

Un i fo rm , ze ro

deg ree imp lan t



1282.3 /0 .568%

V I IS ta 3 0 0 0 H P

1282.3 /0 .568%

V I IS ta 3 0 0 0 H P

1406 .7/

4 .946%

Batch HE Sy stem

1406 .7/

4 .946%

Batch HE Sy stem


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Figure 4 : Precise control requirements in order to obtain uniform distribution within the wafer.

The critical angle is small for the higher energy implants such as the P 600 keV application

outlined below. The critical angle being defined as the maximum angle variation to achieve a

uniform channeled implant. As can be seen, the higher energy results in a smaller critical angle.

Figure 5 : Critical angle requirements for a typical well implant recipe.

600

650

700

6789

10

0.00.51.01.52.0

0 1 2 3 4 5 6 7 8Wafer Tilt (degree)

Uniformity(%)

R(/sq.)

B+, 200keV

Conventional Batch

Parallel Beam

=1.8

=0.6V

=7.7

=1.0V

VIISta 3000 Conventional Batch

SheetResistan

ce

ofN-well

BreakdownVoltage

(n+n-well=0.6m

)

400

395

400405

410415

12V

13V

12V

11V

12V

13V

11V

10V9V

600

650

700

6789

10

0.00.51.01.52.0

0 1 2 3 4 5 6 7 8Wafer Tilt (degree)

Uniformity(%)

R(/sq.)

B+, 200keV

Conventional Batch

Parallel Beam

=1.8

=0.6V

=7.7

=1.0V


SheetResistan

ce

ofN-well

BreakdownVoltage

(n+n-well=0.6m

)

400

395

400405

410415

12V

13V

12V

11V

12V

13V

11V

10V9V

=1.8

=0.6V

=7.7

=1.0V


SheetResistan

ce

ofN-well

BreakdownVoltage

(n+n-well=0.6m

)

400

395

400405

410415

12V

13V

12V

11V

12V

13V

11V

10V9V

Device Isolation Challenges for 65 nm Technology Node, Dr. Takashi Kuroi, et.al. Mitsubishi, Dec. 2002

Critical angle for P, 600keV = 0.5 deg.Critical angle for P, 600keV = 0.5 deg.

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=

E

NdpeZZkc

E

2/12

21

=

E

NdpeZZkc

E

Source: Robert Simonton and Al F. Tasch, ChannelingEffects in Ion Implantation into S il icon, in IONIMPL NATATION: Science and Technology 6 th Edition,293-308

Where Z1, and Z2 are the atomic numbers of theincident ions and the target atoms respectively, e is theelectronic charge, N is the density of target atoms, and

dp is the separation between the planes of atoms thatform the channel walls


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As outlined in the angle control summary below the total angle variation for the batch systems

will not meet the device requirements. The 1.5 degree disk is larger than the critical angle.

Figure 6 : The total angle variation on batch vs. single wafer systems.

Since the device fabrication requirements are becoming more challenging even a 0.5 degree angle

variation has a significant impact on the well profile. The critical channeling angle becomes

small as the energy increases. Even a small angle variation can cause ion de-channeling.

Total Angle Variation on High Energy Implanters

- Batch vs. Single -

0.0

0.51.0

1.5

2.0

2.5

3.0

3.5

4.0

Batch HE - Regular Batch HE w/ 1.5 deg VIISta 3000HP

A

ngleVariation[deg]

Crystal Orientation

Beam Divergence

Beam Parallelism

Mechanics

Cone Angle


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Figure 7 : Angle variation requirements vs. batch system performance.

II. WELL IMPLANT APPLICATION SPACE

There are an increasing number of well applications that will fall under the energy range and dose

capability of medium current ion implantation as shown in Figure 8. The use of triple well

architecture for most planar CMOS fabrication has necessitated the use of MeV implants for the

n-tub that contains both the shallower n and p-wells. These MeV implants has been the major

workhorse for cost effective substrate isolation schemes for both DRAM and Flash memory

1050206020 Varian/J.Olson, slot 1, overlay

1E+14

1E+15

1E+16

1E+17

1E+18

0 5000 10000 15000 20000 25000 30000 35000

DEPTH (Angstroms)

0.75 center

0.75 bottom

0.75 right

0.75 top

0.75 left

0.25 center

0.25 bottom

0.25 right

0.25 top

0.25 left

0.5 deg

0 deg

Critical angle for P, 600keV = 0.5 deg.

Angle Variation on a Typical Batch Implanter


1E+14

1E+15

1E+16

1E+17

1E+18

0 5000 10000 15000 20000 25000 30000 35000

DEPTH (Angstroms)

0.75 center

0.75 bottom

0.75 right

0.75 top

0.75 left

0.25 center

0.25 bottom

0.25 right

0.25 top

0.25 left

0.5 deg

0 deg


1E+14

1E+15

1E+16

1E+17

1E+18

0 5000 10000 15000 20000 25000 30000 35000

DEPTH (Angstroms)

0.75 center

0.75 bottom

0.75 right

0.75 top

0.75 left

0.25 center

0.25 bottom

0.25 right

0.25 top

0.25 left

0.5 deg

0 deg

Critical angle for P, 600keV = 0.5 deg.Critical angle for P, 600keV = 0.5 deg.

Angle Variation on a Typical Batch Implanter


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manufacturing. Until recently, high energy ion implantation, unlike most of the low and medium

dose applications, have used so called batch systems, where several (13-17 wafers) are loaded on

to a disc that rotates at high speed during the ion implant process. The mechanics of wafer

scanning through the ion beam and the design limitations inherent to this approach result in a

variation of 1-1.5 across the wafer [3]. Due to this reason, conventional batch disc high-energy

ion implanters are primarily dedicated to the somewhat angle insensitive deep triple wells, while

the more sensitive threshold voltage, well, and pocket implants are all processed on the single

wafer parallel beam system. The higher cost of high-energy ion implanter coupled with the

limited process steps on these tools naturally has an adverse effect on the cost of ownership. For

example, in a typical implant sequence for DRAM and flash memory only 2-3 steps are in the

unique energy regime of high energy implanter (beyond the capability of medium current

machine), while for most logic chip manufacturing this reduces to one. With the trend in

reduction of energies for the next technology node it can be seen in Figure 9 that future well

applications will fall within the extended operating range of the medium current implanter.

The introduction of VIISta 3000HP single wafer implanter has thus for the first time enabled chip

manufacturers to maximize the utilization of high-energy systems. Both the VIISta 3000 and

VIISta 810XE implanters deliver a parallel, uniform ion beam across a 200 and 300mm wafer by

employing a corrector magnet and high speed electrostatic ion beam scanning technologies with

the details being reported elsewhere [4,5]. These features along with the patented Varian

Positioning System allows for an angle control across the entire operational energy range.

Identical dose control and glitch recovery mechanisms are used in these implanters and allows for

complete transfer of implant processes across these machines for all critical layers. In addition,

the single wafer architecture now enables high tilt pocket and halo implants (up to 60 tilt) to be

processed on both the high energy and medium current implanters. As device geometries scale,

required defect control in terms of elimination of foreign material has accelerated; both VIISta


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3000 and VIISta 810 series of implanters demonstrate identical low levels of particle and metal

contamination for all process steps. In addition, the common control system used on the VIISta

platform allows identical interface of these tools to factory automation systems thus allowing for

easy integration of implant process steps and process transferability.

Figure 8 : An overview of the process applications space covered by high energy and medium

current ion implantation.

Figure 9 : A typical process recipe list for n-well and p-well applications and the relevant trends

in reduced energies as the next technology node is approached.

1 .0E+11

1 .0E+12

1 .0E+13

1 .0E+14

1 .0E+15

1 .0E+16

1 .0E+17

0.1 1 1 0 10 0 1000 1 0000

Contact/PlugBF2, P

S D E E n gB, BF2 , As ,

C, Xe , F , N, Sb

Channe l Eng.B, P, BF2, As, In, Sb

T w i n W e l lB , P

D o p i n g A p p l i c a t i o n s S p a c e 9 0 n m

C C DB , P

D/ We l lP

GateB, P, Ge, AsB - G a p

E n g .Ge, C, N

Isolat ionB, P,

H A L O / P o c k e tB, BF 2, P, As, In

Energy (keV)

Dose(at

oms/cm

2)

S /DB, BF2 , P , As

M / C S p a c e

H / C S p a c e

H / E S p a c e

9 0 n m

Device Type n-well p-well deep-well

CustomerCustomer 1 Logic 500/2E13 175/2.5E13

Customer 2 Logic 650/5.2E13 360/1E14

Customer 3 Logic 600/4E12 420/1.4E13 2000/2E13

Customer 4 Logic 500/4E13 300/3.5E13

Customer 5 Logic 600/4.6E13 305/1E14

Customer 6 DRAM 800/1E12 400/2E13 1200/1E13

Customer 7 DRAM 500/2.5E13 260/1.5E13 1500/5E13

Customer 8 DRAM 500/2.5E13 260/1.5E13 1500/1.5E13

Customer 9 FLASH 600/5E12 420/2E13 2000/2E13

Customer 10 FLASH 700/7E13 360/1E13 1900/1E13

Falls within current energy range (B+ = 270 keV, P++ = 540 keV)

Falls within VIISta 810XE extended e nergy range option (B+ = 300 keV, P++ = 600 keV)

Will likely fall w ithin VIISta 810XE extended energy range option at ne xt technology node


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III. PROCESS TRANSFERABILITY

Process transferability between VIISta 3000 and 810 series of implanters are shown over the

common energy range with Secondary Ion Mass Spectroscopy (SIMS) and four point probe

measurements. Implants were conducted on crystalline n or p-type 300mm wafers either at

normal incidence (referred to as 0 tilt) or at high tilt. SIMS measurements were conducted on

as-implanted wafers, while these were annealed in a RTP system at 1100C; 10 seconds for four

probe point measurements.

Utilization of implanters and the advantages of process transferability were modeled for a typical

flash memory and low power logic recipe set with a proprietary bay capacity model.

IV. PROCESS RESULTS

Figure 10 is a plot of SIMS profiles obtained from 3 points across the wafer (center, and +/- 3mm

from the edges with all three points on a line corresponding to the fast scan direction) for a

540keV B+ implant at zero degree tilt angle on a VIISta 3000 and VIISta 810. The two major

components of the dopant profiles are formed due to dechanneled and channeled ions. The

relative populations of these peaks are dependent on the incident angle of the ion beam, as the

beam incident angle deviates away from normal incidence, the relative population of channeled

boron ions is reduced and that of dechanneled ions increases. These ratios substantially change as

the incident angle is varied by as little as 0.2 degrees. The complete overlap of the SIMS profiles

at all points across the wafer and between VIISta 810 and 3000 arise from the total control of

incident angle in a closed-loop fashion. In contrast, for a traditional batch implanter typical angle

variation of 1-1.5 degrees is reported and this precludes the implementation of true zero degree

implants. In similar vein, SIMS profiles for a typical n-well implant are shown in Figure 11 [6].

Again for this zero degree phosphorus implant, the SIMS profiles are identical between the two

implanters.


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1E+14

1E+15

1E+16

1E+17

1E+18

0.0 0.5 1.0 1.5 2.0 2.5Depth (m icrons)

Concentration(ato

ms/cm

3)

1E+14

1E+15

1E+16

1E+17

1E+18

1E+19

0 0.5 1 1.5 2 2.5

Depth (um)

Concentration(atoms/cc)

Figure 10 :SIMS profiles of a B+, 540keV, 5E13cm

-2implanted at a nominal tilt of zero degree

on VIISta 810 and VIISta 3000. Profiles are obtained at center and 3mm from the edge (left

and right) for wafers processed on both implanters

Figure 11 : SIMS profiles of a n-well implant (P+, 400keV, 1E13cm

-2) implanted at a nominal tilt of zero

degree on VIISta 810 and VIISta 3000. Profiles are obtained at center and 3mm from the edge (left and

right) for wafers processed on both implanters


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As already mentioned single wafer architecture enables high tilt implants employed in

applications such as pocket and halo doping. In Figure 12, SIMS profiles obtained for a B+,

35keV at a 30 nominal implant angle from both VIISta 810 and VIISta 3000 are plotted. The

dopant profiles produced by these implanters are identical, and thus demonstrate the ability to

transfer these layers across these tools.

In Table 1, sheet resistance values for some typical dechanneled, channeled, and high tilt implants

are listed. These values are obtained without conducting a dose matching exercise between the

machines. As can be seen from these values, the implanters are well matched and this arises from

the architectural and dose control commonality designed into the VIISta platform.

Figure 12 : SIMS profiles of a high tilt implant (B+, 35keV, 2E13cm

-2at 30 degree tilt) on VIISta 810

V

1.00E+14

1.00E+15

1.00E+16

1.00E+17

1.00E+18

1.00E+19

0 100 200 300 400 500 600 700

Depth (nm)

Concentration(atoms/cc)


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Table 1: Sheet Resistance Values for Typical Implants

Sheet Resistance (ohms/sq)

VIISta 3000 VIISta 810

B

+

, 400keV, 5E13cm

-2

, 7/23 780 783B+, 400keV, 5E13cm-2, 7/23 829 827

P+, 400keV, 1E14cm-2, 7/23 406 410

B+, 540keV, 3E13cm

-2, 0/0 665 660

B+, 70keV, 3E13cm

-2, 0/0 1145 1148

B+, 45keV, 2E13cm-2, 30/0 2200 2198

P+, 50keV, 1.5E13cm

-2, 25/0 1401 1420

V. OPTIMIZING FOR PRODUCTIVITY

The equivalent process performance of the VIISta 810 and VIISta 3000 allows for complete

process transferability in the overlapping energy and dose regime. This range is 10-300keV for

boron, 10-900keV for phosphorus/arsenic implantation and is determined by common productive

regimes of these machines. For energies below 10keV, all medium and low dose applications are

dedicated to the VIISta 810, while at higher energies such as up to 300keV for boron and 600

KeV for phosphorous, there are substantial throughput benefits when running recipes on a

medium current machine. As can be seen in Figure 13 and Figure 14 there are major productivity

gains realized in the B300 and P600 range with the VIISta 810XE operating at mechanical limit

for the recipes shown. This represents a significant throughput advantage over traditional high

energy machines. Also, compared to medium current machines which lack the extended energy

range capability, there can be a 4X to 8X gain in productivity.

In addition, for double charge Boron (> 300 KeV) and triple charge Phos (> 600 keV), the VIISta

810XE system can provide reasonable throughput performance to provide high energy back-up

capability.


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300keV 3.5E13 Boron

0

50

100

150

200

250

300

350

400

450

Competitor HE System Competitor MC System VIISta 810XE

Throughput(WPH)

Figure 13: A productivity comparison between conventional HE or MC machines and the VIISta

810XE system for a Boron 300 keV P-Well implant.

600keV 1E13 Phos

0

50

100

150

200

250

300

350

400

450

Competitor HE System Competitor MC System VIISta 810XE

Throughput(WPH)

Figure 14: A productivity comparison between conventional HE or MC machines and the VIISta

810XE system for a Phos 600 keV N-Well implant.


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V. DOSE COMPENSATION CAPABILITY

There are additional challenges faced when running photoresist wafers under the recipe

conditions referenced above. High energy impact of primary ions into the photoresist generates

significantly higher levels of outgassing than implants performed at more traditional low energies

(< 200 keV). Although this effect is intuitively obvious, it has significant ramifications for the

design of a beam line, process chamber and compensation algorithms. In particular, it is critical

that the control of photoresist outgassing be ensured to prevent undesired energy contamination,

non-uniformity and dose shifts during implant.

The impact of photoresist outgassing on dose control performance is realized from the faraday

reading not measuring the entire dopant flux. The degree of outgassing oscillates as the ion beam

interacts with varying photoresist areas. This results in compromised dose uniformity. The

VIISta 810XE product offers a unique dose compensation algorithm that controls dose shift (Rs

shift) when operating under challenging conditions of photoresist wafers (see Figure 15)

subjected to high powered beams.

Figure 15: Dose compensation performance with photoresist for a P++

500 keV, 5E13 recipe

condition.

P R w a f er

P R wa fer , w ith 8 10 X E im pr ov em en ts b a r e w a fer

P + + 5 0 0 k e V 5 E 1 3 V e r t ic a l D i a m e t e r S c a n

B e a m C u rre n t - 5 2 0 p u A

- 3 . 50%

- 3 . 00%- 2 . 50%

- 2 . 00%

- 1 . 50%

- 1 . 00%- 0 . 50%

0 . 0 0 %0 . 5 0 %

1 . 0 0 %

0 1 0 2 0 3 0 4 0 5 0 6 0

D ia m e te r S c a n - W a f er M e a s u r e m e n t P o i n ts

%R

sShift

B a r e W a fe r

P R W a fe r D o se C om p O ff

P R W a fe r D o se C om p O n


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The VSEA approach to dose compensation provides a simple, well characterized method to

compensate for photoresist outgassing. Since the technique involves the direct measurement of

current, there is no need for experiments to derive the charge exchange cross section variables.

There is also no requirement for real time pressure measurement which can be inherently unstable

and subject to data corruption by system electrical disturbances.

A one-time system characterization has been performed at the factory and is independent of

species, dose and energy range. The compensation applied is insensitive to absolute pressure and

photoresist conditions. The compensation algorithm (see Figure 16) is recipe selectable, allowing

for flexibility in determining when the compensation shall be applied.

Figure 16 : A simplified overview of the Dose Compensation System algorithm utilized on the

VIISta 810XE..

VI. HIGH ENERGY TO MEDIUM CURRENT PROCESS TRANSFERS

In Figure 17, a typical allocation for a 300mm manufacturing facility with a combination of Flash

and Logic devices is shown. The flash implant recipe set consists of 22 low and medium dose

implants with only one implant that is in the exclusive process regime of the VIISta 3000, while

other implants can be achieved either on the VIISta 3000 or VIISta 810, albeit with different

productivity levels. A similar distribution of recipes also applies to the Logic manufacturing

Dose ControlAlgorithm

IB

DetermineEffective

Dose Rate

One-Time Characterizationof System Requirements at VSEA Species

Dose Energy RangeCompensation parametersfixed

RecipeSelectableFeature


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process. In general, especially in the medium dose regime, the VIISta 810 provides better

productivity with lower cost of ownership. The number of high-energy implanters required as the

capacity is scaled from 1000 wafers/week to 6000 wafers/week remains constant. As the capacity

is scaled upward, more and more implants are transferred to the lower cost medium current

implanter. In all cases, the ability of VIISta 3000 to process all medium current implants enable

the reduction in the number of medium current implanters required, while maintaining

manufacturing redundancy by incorporating at least 2 implanters of a kind at all times in

production. In addition to the direct benefits in reduced number of processing tools, there are also

significant benefit and savings due to commonality of tool components, parts, and training. This

ability to optimize two different processing tools naturally reduces initial capital outlay, overall

cost of ownership, and increases manufacturing flexibility in the era of rapid changes due to

market demand fluctuations.

Figure 17 : Model for number of medium current and high energy tool required as a function of

wafer starts for a 50% logic/flash manufacturing. The bottom part of each bar shows the number

of VIISta 3000s required. The top part of each bar shows the number of VIISta 810s required.

2 2 2 2 2 2

2 2

3

4

5

6

0

1

2

3

4

5

6

7

8

9

1K 2K 3K 4K 5K 6K

Wafer Starts per Week

TotalNumberofImplantersRequired

VIISta 810

VIISta 3000


19/19

19

VI. CONCLUSIONS

In this paper we have reviewed how the new breed of medium current VIISta 810XE implanter

allows for transferability of recipes which were formerly considered as dedicated to high energy

machines. A paradigm shift has occurred in the way in which traditional medium current and

high energy recipes have been dedicated to their respective tool sets. There is now greater

flexibility provided in selecting which tool set the high energy recipes can be run on. Specifically

for twin well applications there are significant productivity gains which can be realized by

employing this new strategy. The process flexibility in turn allows for maximum utilization of

the implanters and a reduced capital investment requirement for a given fab capacity. There are

also device fabrication requirements which should be considered when examining trade-offs

between single wafer vs. batch ion implanters for well applications.

REFERENCES

[1] ITRS Roadmap for Semiconductors 2002 http://public.itrs.net/files/2001itrs/home.htm

[2] V. R. Chavva, S. Norasetthekul, Y. K. Kim, J. Flanagan, and N. Variam, Optimization of

Well and Channel Implants for Maximum Productivity: Process Transferability of Low and

Medium Dose Implants.

[3] T. Yamashita, M. Kitazanwa, Y. Kawasaki, H. Takashino, T. Kuroi, Y. Inoue, M. Inuishi

Advanced Retrograde Well Technology for 90-nm node Embedded SRAM by High Energy

Parallel Beam,Japanese Journal of Applied Physics , Part 1, Vol.41, no.4B p.23999-403..

[4] J. C. Olson and A. Renau, Control of Channeling Uniformity for Advanced Applications,

Proc. of 13th

Int. Conf. on Ion Implantation Technology, Alpbach, Austria, October 2000: pp.

670-673.

[5] J. Weeman, J. Olson, B. N. Guo, U. Jeong, G. C. Li, and S. Mehta, Precise Beam Incidence

Angle Control on the VIISta 810HP, Proc. of 41th

Int. Conf. on Ion Implantation

Technology, Taos, New Mexico, September 2002: pp. 276-278.

[6] N. Variam, S. Mehta, S. Norasethekul, and B. N. Guo, Seamless Transferability of Doping

Processes between the VIISta Platform of Ion Implanters, Proc. of 14th

Int. Conf. on Ion

Implantation Technology, Taos, New Mexico, September 2002: pp. 1283-286.

high productivity for well implant applications varian medium current position paper

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